1. Field of the Invention
The invention refers to a monitoring device with an optical sensor for the detection of interference arcs in electrical systems, particularly in enclosed, SF.sub.6 -insulated high voltage systems, containing a gas-tight installed photoconductor to lead out the interference light.
2. Description of the Prior Art
The increasing energy density in the interconnection as well as the transition to higher transmission voltages make it necessary to improve the protection of the power supply system. In this context, it is essentially a question of increasing the reliability of the protection of the power supply system. The sensing devices used in the system protection, such as sensors for the detection of interference arcs in electrical systems, belong among the essential and most important components for the functional safety of the system as the first member in the path of the signal flow.
A system is described in the German Disclosure Publication No. 24 47 240 where a photoconductor is used as a sensor for the detection and signaling of a light occurring in an enclosed container. A functional monitoring of the sensor is not effected. However, due to the reasons given in the introduction, it has become necessary in the meantime to improve the protection of the system and thus to also include the sensors into a functional control besides the central unit of the protection system.
Furthermore, the German Disclosure Publication No. 22 16 238 contains a system for the protection of enclosed, pressure gas insulated electrical systems against interference arcs the sensors of which consist of a light-sensitive element, for example, a photocell. The light-sensitive elements arranged within the enclosure of an electrical system are each provided directly with a light source as a functional control. The light-sensitive element, for example, a photocell, as well as the light source used for test purposes, for example, an electric bulb, are active parts of the sensor and thus are subject to wear which reduces the reliability of the sensor; the sensor must, therefore, be replaced at certain time intervals for which purpose the enclosure of the electrical system must be opened which proves to be costly.